Open MPI “Hello, World!” is not compiling

Question

Here is a simple MPI "Hello, World!" program.

#include <stdio.h>
#include <mpi.h>

int main(int argc, char **argv)
{
   int size, rank;
   MPI_Init(&argc, &argv);
   MPI_Comm_size(MPI_COMM_WORLD, &size);
   MPI_Comm_rank(MPI_COMM_WORLD, &rank);
   printf("SIZE = %d RANK = %d\n",size,rank);
   MPI_Finalize();   
   return(0);
}

However, it doesn't seem to compile:

Undefined                       first referenced
 symbol                             in file
MPI::Datatype::Free()               /var/tmp//ccE6aG2w.o
MPI::Win::Free()                    /var/tmp//ccE6aG2w.o
MPI::Comm::Comm()                   /var/tmp//ccE6aG2w.o
ld: fatal: symbol referencing errors. No output written to main
collect2: ld returned 1 exit status

I've googled a lot, viewed mailing lists, thousands of them. They say libmpi_cxx is not linking. But it's in the compiler flags.

Here is --showme data:

mpic++ --showme:compile
-I/usr/openmpi/ompi-1.5/include -I/usr/openmpi/ompi-1.5/include/openmpi

mpic++ --showme:link
-R/opt/mx/lib -R/usr/openmpi/ompi-1.5/lib -L/usr/openmpi/ompi-1.5/lib -lmpi -lopen-rte -lopen-pal -lnsl -lrt -lm -ldl -lsocket -lmpi_cxx

My compiler is g++.

Could you show us the complete command line(s) you use to compile and link this code? As written, your code should be able to compile and link with mpicc, since it makes no reference to the C++ bindings. — Phil Miller

DOOM DOOM · Accepted Answer · 2012-12-25T09:19:22

Just place the mpi.h header file above all header files sometimes that causes problem to compile

I am not sure how u execute your code. Compiling

mpic++ your_code_file.c

Execution

mpirun -np <no. of Processors> ./a.out

Open MPI “Hello, World!” is not compiling

3 Answers